(M99) The period in which the Carthaginians first carried their arms into Sicily is not exactly known.(607) All we are certain of is, that they were already possessed of some part of it, at the time that they entered into a treaty with the Romans; the same year that the kings were expelled, and consuls appointed in their room, _viz._ twenty-eight years before Xerxes invaded Greece. This treaty, which is the first we find mentioned to have been made between these two nations, speaks of Africa and Sardinia as possessed by the Carthaginians; whereas the conventions with regard to Sicily, relate only to those parts of the island which were subject to them. By this treaty it is expressly stipulated, that neither the Romans nor their allies shall sail beyond the Fair Promontory,(608) which was very near Carthage; and that such merchants, as shall resort to this city for traffic, shall pay only certain duties which are settled in it.(609) It appears by the same treaty, that the Carthaginians were particularly careful to exclude the Romans from all the countries subject to them; as well as from the knowledge of what was transacting in them; as though the Carthaginians, even at that time, had taken umbrage at the rising power of the Romans; and already harboured in their breasts the secret seeds of that jealousy and distrust, that were one day to burst out in long and cruel wars, and a mutual hatred and animosity, which nothing could extinguish but the ruin of one of the contending powers. (M100) Some years after the conclusion of this first treaty, the Carthaginians made an alliance with Xerxes king of Persia.(610) This prince, who aimed at nothing less than the total extirpation of the Greeks, whom he considered as his irreconcilable enemies, thought it would be impossible for him to succeed in his enterprise without the assistance of Carthage, whose power was formidable even at that time. The Carthaginians, who always kept in view the design they entertained of seizing upon the remainder of Sicily, greedily snatched the favourable opportunity which now presented itself for their completing the reduction of it. A treaty was therefore concluded; wherein it was agreed that the Carthaginians were to invade, with all their forces, those Greeks who were settled in Sicily and Italy, while Xerxes should march in person against Greece itself.